Don't know why you can't quote my post??? Try again as I was looking at it a few minutes ago.

The photo in my post above is an actual "screenshot" of the output from my Zeitronix unit. As you can see, mine is working OK. It wasn't happy when I was running points/condenser, but now the Pertronix trigger and 45 kv coil feeding the MSD box sends the Zeitronix unit a nice, clean square wave. It provides an RPM readout, which is the "X" axis, and the a/f ratio provides the "Y" axis in real time while testing.

The Innovate unit is complete and self contained, while the Zeitronix unit needs a laptop to provide readout. I looked at the Innovate unit, but liked the laptop idea...............and the cheaper price...................with the Zeitronix, so I bought one of those.

Very interesting and much more complex than I've ever seen in other explanations. In agreement with what you said above. I never realized that you had to look way down to the base of the porcelain, with a flashlight and magnifying glass to really make an accurate appraisal of what's going on. Of course, that assumes fresh, clean plugs!